Selective gate spacers for semiconductor devices

ABSTRACT

Techniques related to forming selective gate spacers for semiconductor devices and transistor structures and devices formed using such techniques are discussed. Such techniques include forming a blocking material on a semiconductor fin, disposing a gate having a different surface chemistry than the blocking material on a portion of the blocking material, forming a selective conformal layer on the gate but not on a portion of the blocking material, and removing exposed portions of the blocking material.

CLAIM OF PRIORITY

This application is a continuation of, and claims priority to, U.S.patent application Ser. No. 15/506,101, filed on 23 Feb. 2017 and titled“SELECTIVE GATE SPACERS FOR SEMICONDUCTOR DEVICES”, which is a NationalPhase Entry of, and claims priority to, PCT Application No.PCT/US14/57585, filed on 26 Sep. 2014 and titled “SELECTIVE GATE SPACERSFOR SEMICONDUCTOR DEVICES”, which are incorporated herein by referencein their entireties for all purposes.

TECHNICAL FIELD

Embodiments of the invention generally relate to forming selective gatespacers and more particularly relate to providing a blocking material ona semiconductor fin such that a selectively formed gate spacer may bedisposed on a subsequently formed gate, and device structures, devices,and systems formed using such techniques.

BACKGROUND

Current integrated operations for replacement gate processes in tri-gatetransistor fabrication may include several steps that are complicatedand make it difficult to achieve desired structures. For example, incurrent processes, a dielectric gate spacer material may be depositedover a sacrificial (e.g., dummy) gate as well as the fin in the sourceand drain contact regions of the fin. The deposition may benon-selective such that the dielectric gate spacer material is formedover desired regions (e.g., the sacrificial gate) and undesired regions(e.g., the source and drain contact regions of the fin). Subsequently,the gate spacers may be formed using a multi-step (e.g., anapproximately 10-step) process to form the desired gate spacers suchthat the sacrificial gate may be removed and replaced and subsequentdevice fabrication may continue.

Such multi-step processes may be difficult, costly, and may cause damageto the fin (e.g., damage to the channel region of the fin and/or to thesource/drain region of the fin) and increased defect levels and thelike.

As such, there is a need to achieve simpler, less costly, and higherquality processes for forming tri-gate transistor devices. Such effortsmay become critical as the demand for such devices continues to grow.

BRIEF DESCRIPTION OF THE DRAWINGS

The material described herein is illustrated by way of example and notby way of limitation in the accompanying figures. For simplicity andclarity of illustration, elements illustrated in the figures are notnecessarily drawn to scale. For example, the dimensions of some elementsmay be exaggerated relative to other elements for clarity. Further,where considered appropriate, reference labels have been repeated amongthe figures to indicate corresponding or analogous elements. In thefigures:

FIGS. 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, and 1J are views of exampletransistor structures as particular fabrication operations areperformed;

FIGS. 2A, 2B, 2C, 2D, 2E, and 2F are views of example transistorstructures as particular fabrication operations are performed;

FIG. 3 illustrates an example blocking self-assembled monolayermolecule;

FIG. 4 illustrates an example transistor structure with a blockingmaterial having undercuts;

FIG. 5 illustrates an example transistor structure with a sidewallspacer having a tapered portion;

FIG. 6 illustrates an example transistor structure with an implantregion;

FIG. 7 is a flow diagram illustrating an example process for forming adevice structure using a double patterning technique;

FIG. 8 is an illustrative diagram of a mobile computing platformemploying an IC with transistor(s) fabricated via selective gate spacertechniques; and

FIG. 9 is a functional block diagram of a computing device, all arrangedin accordance with at least some implementations of the presentdisclosure.

DETAILED DESCRIPTION

One or more embodiments or implementations are now described withreference to the enclosed figures. While specific configurations andarrangements are discussed, it should be understood that this is donefor illustrative purposes only. Persons skilled in the relevant art willrecognize that other configurations and arrangements may be employedwithout departing from the spirit and scope of the description. It willbe apparent to those skilled in the relevant art that techniques and/orarrangements described herein may also be employed in a variety of othersystems and applications other than what is described herein.

Reference is made in the following detailed description to theaccompanying drawings, which form a part hereof, wherein like numeralsmay designate like parts throughout to indicate corresponding oranalogous elements. It will be appreciated that for simplicity and/orclarity of illustration, elements illustrated in the figures have notnecessarily been drawn to scale. For example, the dimensions of some ofthe elements may be exaggerated relative to other elements for clarity.Further, it is to be understood that other embodiments may be utilizedand structural and/or logical changes may be made without departing fromthe scope of claimed subject matter. It should also be noted thatdirections and references, for example, up, down, top, bottom, over,under, and so on, may be used to facilitate the discussion of thedrawings and embodiments and are not intended to restrict theapplication of claimed subject matter. Therefore, the following detaileddescription is not to be taken in a limiting sense and the scope ofclaimed subject matter defined by the appended claims and theirequivalents.

In the following description, numerous details are set forth. However,it will be apparent to one skilled in the art, that the presentinvention may be practiced without these specific details. In someinstances, well-known methods and devices are shown in block diagramform, rather than in detail, to avoid obscuring the present invention.Reference throughout this specification to “an embodiment” or “oneembodiment” means that a particular feature, structure, function, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. Thus, the appearances ofthe phrase “in an embodiment” or “in one embodiment” in various placesthroughout this specification are not necessarily referring to the sameembodiment of the invention. Furthermore, the particular features,structures, functions, or characteristics may be combined in anysuitable manner in one or more embodiments. For example, a firstembodiment may be combined with a second embodiment anywhere theparticular features, structures, functions, or characteristicsassociated with the two embodiments are not mutually exclusive.

As used in the description of the invention and the appended claims, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willalso be understood that the term “and/or” as used herein refers to andencompasses any and all possible combinations of one or more of theassociated listed items.

The terms “coupled” and “connected,” along with their derivatives, maybe used herein to describe structural relationships between components.It should be understood that these terms are not intended as synonymsfor each other. Rather, in particular embodiments, “connected” may beused to indicate that two or more elements are in direct physical orelectrical contact with each other. “Coupled” my be used to indicatedthat two or more elements are in either direct or indirect (with otherintervening elements between them) physical or electrical contact witheach other, and/or that the two or more elements co-operate or interactwith each other (e.g., as in a cause and effect relationship).

The terms “over,” “under,” “between,” “on”, and/or the like, as usedherein refer to a relative position of one material layer or componentwith respect to other layers or components. For example, one layerdisposed over or under another layer may be directly in contact with theother layer or may have one or more intervening layers. Moreover, onelayer disposed between two layers may be directly in contact with thetwo layers or may have one or more intervening layers. In contrast, afirst layer “on” a second layer is in direct contact with that secondlayer. Similarly, unless explicitly stated otherwise, one featuredisposed between two features may be in direct contact with the adjacentfeatures or may have one or more intervening features.

As used in throughout this description, and in the claims, a list ofitems joined by the term “at least one of or” one or more of can meanany combination of the listed terms. For example, the phrase “at leastone of A, B or C” can mean A; B; C; A and B; A and C; B and C; or A, Band C.

Methods, device structures, devices, apparatuses, and computingplatforms, are described below related to selectively formed gatesidewall spacers.

As described above, there is a need to achieve simpler, less costly, andhigher quality processes for forming tri-gate transistor devices andsimilar devices. As is discussed further herein, in an embodiment, ablocking material may be formed on a semiconductor fin. For example, theblocking material may have a different surface chemistry than asubsequently formed gate. The blocking material may be any materialhaving a different surface chemistry with respect to the subsequentlyformed gate such that a conformal layer may be formed on the gate butnot on (or at least not on portions of) the blocking material. Forexample, the blocking material may be characterized as a cladding of thefin or the like. As discussed, a gate may be disposed on a portion ofthe blocking material (e.g., and over a portion of the semiconductorfin) such that, as discussed, the gate and the blocking material havedifferent surface chemistries. In some examples, an optional implant maybe performed to form an implant region within the gate to assist in theselectivity of a subsequently formed conformal layer onto the gate.Furthermore, in some examples, a blocking self-assembled monolayer maybe formed on exposed portions of the blocking material. Such a blockingself-assembled monolayer may include molecules having head groups andtails, as is discussed further herein, such that the head groups attachto the blocking material and the tails further inhibit the formation ofthe subsequent conformal layer. In other examples, no such blockingself-assembled monolayer may be provided.

As discussed, a conformal layer having an etch selectivity with respectto the blocking material may then be selectively formed on the gate butnot on at least portions of the blocking material (e.g., eitherincluding or excluding the blocking self-assembled monolayer) due to thedifferences in surface chemistries as discussed. For example, theconformal layer may not be formed on portions of the fin covered by theblocking material, however, a portion of the conformal layer may beformed on the fin immediately adjacent to the gate. As discussed, thegate itself may be covered by the conformal layer. In some examples, theexposed portions of the blocking material (e.g., and the blockingself-assembled monolayer if used) may be removed via an etch operationbased on the etch selectivity between the blocking material and theconformal layer.

Subsequently, the top portion of the conformal layer may be removed bychemical mechanical polish (CMP) processing or the like. In someexamples, the gate may be a final gate structure and, in other examples,the gate may be a sacrificial (e.g., dummy) gate. In such sacrificialgate examples, the sacrificial gate may be removed and replaced with afinal gate stack such as a high-k gate dielectric and metal gate. Such atransistor structure may be used to subsequently fabricate a transistordevice within an integrated circuit implementing a memory device or alogic device or the like.

For example, an integrated circuit may include a transistor formed usingtechniques discussed herein. Such a transistor may include a gatedisposed over a portion of a semiconductor fin and a gate sidewallspacer adjacent to the gate. Furthermore, the transistor may include ablocking material between the gate sidewall spacer and the semiconductorfin such that the blocking material has an etch selectivity with respectto the gate sidewall spacer. Also, in some examples, a head or tailportion (or both) of a blocking self assembled monolayer molecule may bedisposed between the blocking material and the gate sidewall spacer. Insome examples, the remaining blocking material may include an implantspecies and/or the semiconductor fin may include an implant region atleast under the blocking material. In some examples, the implant regionmay extend within other regions of the fin. Furthermore, the transistormay include an undercut portion under the gate sidewall spacer andwithin the blocking material (e.g., due to removal of adjacent portionsof the blocking material). Also, the gate sidewall spacer may include atapered or rounded portion adjacent to the fin (e.g., due to theconformal layer having limited growth adjacent to the blockingmaterial).

The techniques discussed herein may provide a simplified fabricationprocess for forming gate sidewall spacers adjacent to gates disposed onsemiconductor fins. Such selective gate sidewall spacer techniques mayeliminate fabrication steps that would otherwise cause complication,variability in processing, and/or damage to the semiconductor fin (e g,channel regions and/or source/drain regions of the fin). Devices formedusing such simplified techniques may provide enhanced performance andreduced cost of manufacture. Such transistor structures including gatesidewall spacers and a sacrificial gate may be used in a variety ofprocess flows to fabricate a transistor device.

FIGS. 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, and 1J are views of exampletransistor structures as particular fabrication operations areperformed, arranged in accordance with at least some implementations ofthe present disclosure. FIG. 1A provides a plan view 101 and a side view102 taken along lines A-A′ in plan view 101 of an example transistorstructure 100. As shown in FIG. 1A, transistor structure 100 may includea device layer 103 and a semiconductor fin 104. Device layer 103 mayinclude, for example, a semiconductor material such as crystallinesilicon. In some examples, device layer 103 may include previouslyformed devices, device components, or the like. For example, devicelayer 103 may include transistors, memories, capacitors, resistors,optoelectronic devices, switches, or any other active or passiveelectronic devices, or portions thereof. In some examples, device layer103 may include a partially formed device such as a transistor device.In some examples, device layer 103 may be disposed over a substrate (notshown). In some examples, the substrate may include a semiconductormaterial such as monocrystalline silicon (Si), germanium (Ge), silicongermanium (SiGe), a III-V materials based material (e.g., galliumarsenide (GaAs)), a silicon carbide (SiC), a sapphire (Al₂O₃), or anycombination thereof. In some examples, device layer 103 may itselfcomprise such substrate materials.

Semiconductor fin 104 may include any suitable semiconductor material.In an embodiment, semiconductor fin 104 includes monocrystallinesilicon. In other embodiments, semiconductor fin 104 may include asemiconductor material such as germanium (Ge), silicon germanium (SiGe),a III-V materials based material (e.g., gallium arsenide (GaAs)), asilicon carbide (SiC), a sapphire (Al₂O₃), or any combination thereof.Semiconductor fin 104 may be formed using any suitable technique ortechniques such as via a patterning and etch of device layer 103, via asacrificial fin process, or the like. As illustrated, in some examples,semiconductor fin 104 may be a tri-gate fin disposed on device layer103. In other examples, semiconductor fin 104 may be an undercut finsuch that a portion of device layer 103 may be removed from undersemiconductor fin 104 and semiconductor fin 104 may be characterized asa nanowire and transistor structures as discussed herein may becharacterized as nanowire devices. In some examples, the fin structureof such a nanowire device may have a substantially circular crosssection.

FIG. 1B illustrates a transistor structure 105 similar to transistorstructure 100, after the formation of a blocking material 108 onsemiconductor fin 104. Blocking material 108 may include any suitablematerial or material stack. For example, blocking material 108 mayinclude one or more of silicon oxide, silicon oxynitride, siliconnitride, silicon carbide, silicon oxycarbide, or aluminum oxide. As isdiscussed further below, blocking material 108 may have a difference insurface chemistry with (e.g., may be chemically differentiated with) asubsequently formed gate and blocking material 108 may block or impedethe formation of a conformal layer thereon. For example, thesubsequently formed gate may be a sacrificial gate comprisingpolysilicon. Furthermore, blocking material 108 may protectsemiconductor fin 104 during subsequent processing. In various examples,blocking material 108 may be characterized as a blocking layer or acladding or the like. Blocking material 108 may be formed on a top andsidewalls of semiconductor fin 104. Furthermore, blocking material 108may have any suitable thickness. In some examples, blocking material 108may have a thickness in the range of 2 to 5 nm, a thickness in the rangeof 4 to 10 nm, or a thickness in the range of 5 to 15 nm, or the like.

Blocking material 108 may be formed using any suitable technique ortechniques. In some examples, blocking material 108 may be formed via athermal growth process. For example, blocking material 108 may include asilicon oxide (SiO₂) grown via thermal oxidation. In other examples,blocking material 108 may be deposited using a blanket depositiontechniques such as chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD), physical vapor deposition (PVD),molecular beam epitaxy (MBE), metalorganic chemical vapor deposition(MOCVD), molecular layer deposition (MLD), atomic layer deposition(ALD), or the like.

FIG. 1C illustrates a transistor structure 107 similar to transistorstructure 105, after the formation of a gate 110 on a portion ofblocking material 108. As shown, gate 110 may be patterned onto aportion of blocking material 108. Gate 110 may be disposed on blockingmaterial 108 using any suitable technique or techniques. For example,gate 110 may be formed by the deposition of a bulk material andpatterning using lithography techniques or the like. in some examples,gate 110 may be a sacrificial or dummy gate such that a subsequentreplacement gate process may be performed to form a final gate stack.Gate 110 may include any suitable material having a difference insurface chemistry with respect to blocking material 108 as discussedherein. In some examples, gate 110 is polysilicon. In other examples,gate 110 is silicon nitride. Blocking material 108, gate 110, and otherstructures may wrap around three sides of semiconductor fin 104 (e.g., atop of semiconductor fin 104 as shown in FIG. 1C, and sides ofsemiconductor fin 104—please refer to the plan view of FIG. 1A). In someexamples, gate 110 may extend across multiple semiconductor fins. Insome examples, blocking material 108, gate 110, and other structures maywrap around all sides of semiconductor fin 104 such as in nanowireimplementations.

FIG. 1D illustrates a transistor structure 109 similar to transistorstructure 107, after an optional implant to form an implant region 106within gate 110. As is discussed below with respect to FIG. 1E, aselective conformal layer may be formed on gate 110. In some examples,an optional implant as illustrated may be performed prior to forming theconformal layer on gate 110. For example, the implant species may assistin the formation of the selective conformal layer on gate 110 whilecausing minimal damage and/or minimal change in the chemistry ofimplanted portions of blocking material 108 on semiconductor fin 104.For example, gate 110 may be polysilicon and blocking material 108 maybe silicon oxide (e.g., a thermally grown silicon oxide) or siliconcarbide or the like. In such an example, the implant species of implantregion 106 may be nitrogen. Such an implant may cause the subsequentconformal layer to more selectively form on gate 110 and not on exposedportions of blocking material 108 as discussed herein. In an examples,gate 110 may be polysilicon and the implant may be an amorphization orpre-amorphization implant of the polysilicon with an implant species ofsilicon or nitrogen or an inert implant species such as argon, helium,or xenon, or the like. In such examples, the subsequently formedblocking material 108 (discussed further herein) may be formed by acarbon deposition and rapid thermal processing (e.g., an anneal or thelike) such that blocking material 108 (and subsequently formed gatesidewall spacers) includes silicon carbide. In other examples, thesubsequently formed blocking material 108 may be a thermally grownsilicon oxide or the like.

As discussed, in some examples, the implant may include nitrogen,silicon, or an inert implant species such as argon, helium, or xenon. Inother examples, the implant may include oxygen, boron, phosphorus,arsenic, antimony or carbon. In some examples, the implant may beperformed as a blanket implant such that no patterning is performedprior to the implant. For example, implant region 106 may be provided ona top and sidewalls of gate 110 as shown and the exposed portions of thetop and sidewalls of semiconductor fin 104. In some examples an implantregion (not shown) may extend into blocking material 108 and/orsemiconductor fin 104.

For example, such implant regions are discussed herein with respect toFIG. 6. In some examples, portions of device layer 103 outside ofsemiconductor fin 104 may also include an implant region. Such animplant region or portions thereof may remain after subsequentfabrication steps and may be a part of a final transistor device orstructure as discussed herein. As discussed, the implant illustrated inFIG. 1D may be optional and, in some examples, no implant may beperformed. FIGS. 1E, 1F, 1G, 1H, 1I, and 1J illustrate an exampleembodiment without the optional implant region for the sake of clarityof presentation.

In other examples, the implant discussed with respect to FIG. 1D may besufficient to form a conformal layer disposed on gate 110. As discussed,in some examples, blocking material 108 may include a silicon oxide,gate 110 may include polysilicon, and the implant species of implantregion 106 may include nitrogen. In such examples, a selective conformallayer as discussed herein may be formed via the discussed implant andwithout subsequent deposition operations (or the like) as discussed withrespect to FIG. 1E. Furthermore, such a selective conformal layer formedvia implant may have etch selectivity with respect to blocking material108. For example, as discussed herein, selectively forming a conformallayer on gate 110 may include implanting a species into gate 110 to forman implant region. Such processing may include an optional annealingoperation or the like. In other examples, a conformal layer may beformed on gate 110 (e.g., with or without an implant region) viadeposition operations or the like.

FIG. 1E illustrates a transistor structure 111 similar to transistorstructure 107, after the formation of a selective conformal layer 112 ongate 110. As shown, selective conformal layer 112 may be formed on gate110 and not on portions 113 of blocking material 108. For example,selective conformal layer 112 may be selectively formed on gate 110 andnot on portions 113 of blocking material 108 due to the difference insurface chemistries between gate 110 and blocking material 108 asdiscussed herein. As shown, in some examples, selective conformal layer112 may be formed on portions 114 of blocking material 108. Suchportions may be covered due to the formation of selective conformallayer 112 proximal to portions 114 on gate 110 for example. In otherexamples, selective conformal layer 112 may not be formed on anyportions of blocking material 108. In some examples, selective conformallayer 112 may include a tapered or rounded portion as is discussedfurther herein with respect to FIG. 5. As discussed, blocking material108 may block or impede the formation of selective conformal layer 112thereon. In some examples, as discussed with respect to FIGS. 2A-2F and3, an additional blocking self-assembled monolayer may be formed onblocking material 108 to block or impede the formation of selectiveconformal layer 112 thereon.

Selective conformal layer 112 may include any suitable material ormaterials that may be formed on gate 110 and not on portions of blockingmaterial 108 and that may have an etch selectivity with respect toblocking material 108. For example, selective conformal layer 112 mayinclude one or more of silicon oxide, silicon nitride, siliconoxynitride, silicon carbide, silicon oxycarbide, boron nitride, boroncarbide, boron carbonitride, boron phosphide, boron sulfide,polyphosphazene, or metal oxide such as aluminum oxide. Selectiveconformal layer 112 may have any suitable thickness. In some examples,selective conformal layer 112 may have a thickness in the range of 3 to10 nm, a thickness in the range of 5 to 12 nm, or a thickness in therange of 8 to 20 nm, or the like.

Selective conformal layer 112 may be formed using any suitable techniqueor techniques. In some examples, selective conformal layer 112 may beformed via a deposition using vapor phase methods such as plasmaexposure, ALD, MLD, or CVD. The temperature of such a deposition may beany suitable temperature such as a temperature in the range of roomtemperature to 1100° C. In an example, gate 110 may include polysiliconthat may be exposed to a remote nitrogen gas (N₂) or ammonia (NH₃)plasma with an optional other reactant such as hydrogen (H₂) and/or anoptional diluting inert gas such as helium (He) or Argon (Ar) at atemperature in the range of 400 to 1100° C. for a time in the range of 1to 600 seconds to form a selective layer of silicon nitride on gate 110.In such examples, blocking material 108 may include a silicon oxide,silicon oxynitride, silicon oxycarbide, silicon carbide or a metal oxidesuch as aluminum oxide, for example. In some examples, the discusseddeposition may be followed by rapid thermal processing. For example,selective conformal layer 112 may be formed after a pre-amorphizationimplant of gate 110 such that selective conformal layer 112 may beformed by a deposition (e.g., of carbon) and rapid thermal processing(e.g., to form a silicon carbide conformal layer 112).

Furthermore, as shown, selective conformal layer 112 may be formed via asingle operation such as a single deposition operation. For example, thesingle deposition operation may include an atomic layer deposition, amolecular layer deposition, or a chemical vapor deposition as discussed.Such a single deposition operation may provide for simplicity ofmanufacture and such a single deposition operation in the presence ofblocking material 108 may provide for protection of semiconductor fin104 such that high manufacturing yields and low defectivity may beachieved.

Furthermore, as discussed with respect to FIG. 1D, in some examples,selective conformal layer 112 may be formed by performing an implantinto gate 110. In such examples, a portion of gate 110 may be consumedto form selective conformal layer 112. Furthermore, in such examples, aportion of blocking material 108 may remain between a subsequentlyformed gate sidewall spacer and a portion of semiconductor fin 104 as isdiscussed with respect to FIG. 1J and elsewhere herein.

FIG. 1F illustrates a transistor structure 115 similar to transistorstructure 111, after the removal of exposed portions of blockingmaterial 108. As shown, portions of blocking material 108 may be removedto expose regions 116 of semiconductor fin 104 and to leave a remainingblocking material portion 117. Remaining blocking material portion 117may be under gate 110 and/or under portions of selective conformal layer112. In some examples, as is discussed further herein with respect toFIG. 4, an undercut may be formed within remaining blocking materialportion 117 during the removal of portions of blocking material 108. Theremoved portions of blocking material 108 may be removed via anysuitable technique or techniques. For example, portions of blockingmaterial 108 may be removed via an etch process such as a wet etchprocess. As discussed, selective conformal layer 112 and blockingmaterial 108 may have an etch selectivity therebetween such that an etchmay be performed that removes portions of blocking material 108 whileleaving selective conformal layer 112 substantially unaffected. Forexample, portions of blocking material 108 may be removed via aselective etch operation. Regions of the exposed portions ofsemiconductor fin 104 may subsequently be used for source/drainformation and/or source/drain contacts or the like. The techniquesdiscussed herein may provide for substantially undamaged regions ofsemiconductor fin 104 for such structures.

FIG. 1G illustrates a transistor structure 118 similar to transistorstructure 115, after the optional formation of an interlayer dielectricmaterial 119. As shown, interlayer dielectric material 119 may be bulkdeposited using any suitable technique or techniques over semiconductorfin 104, remaining blocking material portion 117, gate 110, andselective conformal layer 112. Interlayer dielectric material 119 mayinclude any suitable dielectric material for providing electricalinsulation between devices formed on or within device layer 103 forexample. In some examples, such an interlayer dielectric material 119may not be employed or an interlayer dielectric (if used betweendevices) may be provided at a subsequent processing operation.

FIG. 1H illustrates a transistor structure 120 similar to transistorstructure 118, after the exposure of a top 121 of gate 110 and theformation of gate sidewall spacers 122, 123. As shown, a portion ofinterlayer dielectric material 119 and a top of selective conformallayer 112 may be removed. The portion of interlayer dielectric material119 and the top of selective conformal layer 112 may be removed usingany suitable technique or techniques such as, for example, chemicalmechanical polish (CMP) techniques. Also as shown, gate sidewall spacers122, 123 may be formed from remaining portions of selective conformallayer 112 after the removal of a top portion of selective conformallayer 112.

As discussed, interlayer dielectric material 119 may be optional or suchan interlayer dielectric may be provided later in the process flow. Insuch examples, top 121 of gate 110 may be exposed by the removal of atop of selective conformal layer 112 to form gate sidewall spacers 122,123 via chemical mechanical polish (CMP) techniques or the like. In someexamples, other transistor structures such as source and drain implants,extended source and drain regions may be formed with gate 110 presentprior to the formation of interlayer dielectric material 119.

FIG. 1I illustrates a transistor structure 124 similar to transistorstructure 120, after the removal of gate 110 and removal of a portionblocking material portion 117 adjacent to semiconductor fin 104 andbetween gate sidewall spacers 122, 123. As shown, gate 110 may beremoved. In such examples, gate 110 may be a sacrificial gate or a dummygate or the like. Furthermore, as shown, a portion of blocking materialportion 117 may be removed to leave remaining blocking material 125 andremaining blocking material 126 and to expose a region 127 ofsemiconductor fin 104. Gate 110 may be removed using any suitabletechnique or technique such as etch techniques or the like. Similarly,the portion of blocking material portion 117 may be removed using anysuitable technique or technique such as etch techniques or the like. Insome examples, gate 110 may be removed in a first etch process and theportion blocking material portion 117 may be removed in a second etchprocess. In some examples, as is discussed further herein with respectto FIG. 4, an undercut may be formed within remaining blocking material125 and/or remaining blocking material 126 during the removal of theportion blocking material portion 117.

FIG. 1J illustrates a transistor structure 128 similar to transistorstructure 124, after the formation of gate stack 129. As shown, gatestack 129 may be formed on semiconductor fin 104 and between gatesidewall spacers 122, 123. Gate stack 129 may include any suitablematerial or materials. For example, gate stack 129 may include a gatedielectric 130 such as a high-k gate dielectric and a gate electrode 131such as a metal gate electrode. Gate stack 129 may be formed using anysuitable technique or techniques such as conformal deposition,deposition, and CMP techniques or the like. As shown, in some examples,gate dielectric 130 may be formed on a surface of semiconductor fin 104.In other examples, gate dielectric 130 may also be formed on sidesurfaces of gate sidewall spacers 122, 123 such that gate electrode 131is not in direct contact with gate sidewall spacers 122, 123 forexample. As discussed, in some examples, gate stack 129 may wrap aroundthree sides of semiconductor fin 104 (e.g., a top of semiconductor fin104 as shown in FIG. 1J, and sides of semiconductor fin 104—please referto the plan view of FIG. 1A). In some examples, gate stack 129 may wraparound all sides of semiconductor fin 104 such as in nanowireimplementations.

Transistor structure 128 may form a portion of a transistor of anintegrated circuit. for example, as is discussed further herein. Forexample, a transistor may include gate stack 129 (e.g. a gate) formedover a portion of semiconductor fin 104. The transistor may furtherinclude gate sidewall spacer 122 adjacent to the gate (e.g., adjacent togate stack 129) and a blocking material (e.g., blocking material 125)between gate sidewall spacer 122 and another portion of semiconductorfin 104. As discussed, gate sidewall spacer 122 may be formed viadisposing a selective conformal layer on sacrificial gate 110 or viaperforming an implant to form a selective conformal layer on sacrificialgate 110. Such a transistor structure or other transistor structuresdiscussed herein may be implemented via a system, platform, computingdevice, or the like as is discussed further herein.

As discussed, FIGS. 1G-1J illustrate an example process flow for theformation of a transistor structure. In other embodiments, otherfabrication operations may be performed on transistor structure 115 ofFIG. 1F such as other replacement gate process flows or the like. Forexample, as discussed, a top of gate 110 may be exposed, sidewallspacers 122, 123 may be formed, and gate 110 may be removed without theintroduction of interlayer dielectric 119. Furthermore, the formation ofother structures such as channel implant regions, source/drain implantregions, and the like have not been discussed for the sake of clarity ofpresentation.

As discussed above with respect to FIG. 1E, a blocking self-assembledmonolayer may be formed on blocking material 108 to block or impede theformation of selective conformal layer 112 thereon. Such embodiments arediscussed with respect to FIGS. FIGS. 2A-2F and 3.

FIGS. 2A, 2B, 2C, 2D, 2E, and 2F are views of example transistorstructures as particular fabrication operations are performed, arrangedin accordance with at least some implementations of the presentdisclosure. FIG. 2A illustrates a transistor structure 200 similar totransistor structure 109, after the formation of a blockingself-assembled monolayer 201. As shown, blocking self-assembledmonolayer 201 may be selectively formed on exposed portions of blockingmaterial 108. For example, blocking self-assembled monolayer 201 may beselectively formed on exposed portions of blocking material 108 due tothe discussed difference in surface chemistries between blockingmaterial 108 and gate 110. As discussed, blocking self-assembledmonolayer 201 may provide enhanced or additional blocking of theformation of a subsequent conformal layer such that the conformal layeris selectively formed on gate 110 and not on blocking self-assembledmonolayer 201 to thereby increase the selectivity of the subsequentlyformed conformal layer onto gate 110. Blocking self-assembled monolayer201 may include molecules having head groups, tails, and, optionally,functional tail groups and blocking self-assembled monolayer 201 may beorganized onto blocking material 108 such that head groups attach toblocking material 108 and tails and optional functional tail groupsextend away from blocking material 108 in substantially the z-directionillustrated in FIG. 2A. In some examples, blocking self-assembledmonolayer 201 may be characterized as a passivation material or thelike. Furthermore, blocking self-assembled monolayer 201 may be formedusing any suitable technique or techniques. For example, blockingself-assembled monolayer 201 may be formed spontaneously on blockingmaterial 108 via adsorption or the like. For example, blockingself-assembled monolayer 201 may be formed in a solution phase or in avapor phase.

FIG. 3 illustrates an example blocking self-assembled monolayer molecule300, arranged in accordance with at least some implementations of thepresent disclosure. As shown in FIG. 3, blocking self-assembledmonolayer molecule 300 may include a head group 301, a tail 302, and,optionally, a tail functional group 303. As discussed, head group 301may adsorb or otherwise attach to blocking material 108. Head group 301may include any suitable functional group that may attach to blockingmaterial 108 but not to gate 110. For example, head group 301 mayinclude one or more of a siloxane, a silyl chloride, an alkene, analkyne, an amine, a phosphine, a thiol, a phosphonic acid, or acarboxylic acid. Furthermore, tail 302 may include any type and numberof connecting group such as 8 to 22 alkyl groups or the like. Forexample, blocking self-assembled monolayer molecule 300 may have arelatively long (e.g. C8-C22) alkyl chain. Furthermore, blockingself-assembled monolayer molecule 300 may include functional tail group303. In other examples, blocking self-assembled monolayer molecule 300may not include a functional tail group.

Returning to FIG. 2A, in some examples, blocking material 108 may be asilicon oxide (e.g., a thermal oxide having a thickness of 2 to 5 nm) asdiscussed herein. In an embodiment, such a silicon oxide blockingmaterial 108 may be further passivated by the formation of a siloxanebased blocking self-assembled monolayer 201. In such examples, gate 110may be a polysilicon gate such as an H-terminated polysilicon.

As discussed herein with respect to FIG. 1D, in some examples, anoptional implant may be provided to form an implant region within gate110. Such an implant region may assist in the formation of selectiveconformal layer 112 or such an implant may be performed to formselective conformal layer 112. The implant region may include anyimplant species as discussed herein. For example, such an implant may beperformed prior to or subsequent to the formation of blockingself-assembled monolayer 201 when used to assist in the formation ofselective conformal layer 112. In examples where such an implant may beperformed to form selective conformal layer 112, the implant may beperformed subsequent to the formation of blocking self-assembledmonolayer 201. Such an implant region is not illustrated in FIGS. 2A-2Ffor the sake of clarity of presentation.

FIG. 2B illustrates a transistor structure 202 similar to transistorstructure 200, after the formation of selective conformal layer 112 ongate 110. Selective conformal layer 112 may be formed in any manner andmay include any materials and/or characteristics as discussed herein.Such details will not be repeated for the sake of brevity. Continuingthe above example such that blocking material 108 is silicon oxide,blocking self-assembled monolayer 201 includes a siloxane basedmolecules and gate 110 is polysilicon, selective conformal layer 112 maybe formed by a low temperature (e.g., 25 to 300° C.) ALD, MLD, or CVDprocess.

As shown, selective conformal layer 112 may be formed on gate 110 andnot on portions 203 of blocking self-assembled monolayer 201. Forexample, selective conformal layer 112 may be selectively formed on gate110 and not on portions 203 of blocking self-assembled monolayer 201 dueto the difference in surface chemistries between gate 110 and blockingself-assembled monolayer 201 and/or blocking material 108 as discussedherein. As shown, in some examples, selective conformal layer 112 may beformed on portions 204 of blocking self-assembled monolayer 201. Suchportions may be covered due to the formation of selective conformallayer 112 proximal to portions 204 on gate 110 for example. In otherexamples, selective conformal layer 112 may not be formed on anyportions of blocking self-assembled monolayer 201. In such examples,selective conformal layer 112 may include a tapered or rounded portionas is discussed further herein with respect to FIG. 5. As discussed,blocking self-assembled monolayer 201 and/or blocking material 108 mayblock or impede the formation of selective conformal layer 112 thereon.

FIG. 2C illustrates a transistor structure 205 similar to transistorstructure 202, after the removal of exposed portions of blockingself-assembled monolayer 201 and blocking material 108. As shown,portions of blocking self-assembled monolayer 201 and portions ofblocking material 108 may be removed to expose regions 206 ofsemiconductor fin 104 and to leave a remaining self-assembled monolayerportions 207, 208 and remaining blocking material portion 117. Remainingself-assembled monolayer portions 207, 208 may be under portions ofselective conformal layer 112. Remaining blocking material portion 117may be under gate 110 and/or under portions of selective conformal layer112. In some examples, an undercut may be formed within remainingblocking material portion 117 during the removal of portions of blockingmaterial 108.

Furthermore, although illustrated as relatively conformal layers,remaining self-assembled monolayer portions 207, 208 may be only traceamounts of self-assembled monolayer molecules attached or adhered toremaining blocking material portion 117, for example. In some examples,entire molecules of self-assembled monolayer molecules may remain. Inother examples, only portions of molecules (e.g., head groups, tails,functional tail groups, or combinations thereof) may remain in remainingself-assembled monolayer portions 207, 208. The removed portions ofblocking self-assembled monolayer 201 and blocking material 108 may beremoved via any suitable technique or techniques. For example, portionsof blocking material 108 may be removed via an etch process such as awet etch process. As discussed, selective conformal layer 112 andblocking material 108 may have an etch selectivity therebetween suchthat an etch may be performed that removes portions of blocking material108 while leaving selective conformal layer 112 substantiallyunaffected. For example, portions of blocking material 108 may beremoved via a selective etch operation. In some examples, removedportions of blocking self-assembled monolayer 201 may be removed duringthe removal of portions of blocking material 108 using a lift-offtechnique for examples. In other examples, portions of blockingself-assembled monolayer 201 may be removed prior to the removal ofportions of blocking material 108 using wet etch or other dissolutiontechniques.

FIG. 2D illustrates a transistor structure 209 similar to transistorstructure 205, after the formation of an optional interlayer dielectricmaterial 119 and after the exposure of a top 211 of gate 110 and theformation of gate sidewall spacers 122, 123. In some examples,interlayer dielectric material 119 may be bulk deposited using anysuitable technique or techniques over semiconductor fin 104, remainingblocking material portion 117, remaining self-assembled monolayerportions 207, 208, gate 110, and selective conformal layer 112 asdiscussed herein with respect to FIG. 1G. Interlayer dielectric material119 may include any suitable dielectric material for providingelectrical insulation between devices formed on or within device layer103 for example. As shown, a portion of interlayer dielectric material119 (e.g., if bulk deposited) and a top of selective conformal layer 112may be removed. The portion of interlayer dielectric material 119 andthe top of selective conformal layer 112 may be removed using anysuitable technique or techniques such as, for example, chemicalmechanical polish (CMP) techniques. Also as shown, gate sidewall spacers122, 123 may be formed from remaining portions of selective conformallayer 112 after the removal of a top portion of selective conformallayer 112. As discussed with respect to FIGS. 1G and 1H, interlayerdielectric material 118 may not be utilized or an interlayer dielectricmaterial may be provided later in the process flow. In such examples,top 121 of gate 110 may be exposed by removing a top of selectiveconformal layer 112 to form gate sidewall spacers 122, 123.

FIG. 2E illustrates a transistor structure 212 similar to transistorstructure 209, after the removal of gate 110 and removal of a portionblocking material portion 117 adjacent to semiconductor fin 104 andbetween gate sidewall spacers 122, 123. As shown, gate 110 may beremoved. In such examples, gate 110 may be a sacrificial gate or a dummygate or the like. Furthermore, as shown, a portion blocking materialportion 117 may be removed to leave remaining blocking material 125 andremaining blocking material 126 and to expose a region 213 ofsemiconductor fin 104. Gate 110 may be removed using any suitabletechnique or technique such as etch techniques or the like. Similarly,the portion blocking material portion 117 may be removed using anysuitable technique or technique such as etch techniques or the like. Insome examples, gate 110 may be removed in a first etch process and theportion blocking material portion 117 may be removed in a second etchprocess. In some examples, as is discussed further herein with respectto FIG. 4, an undercut may be formed within remaining blocking material125 and/or remaining blocking material 126 during the removal of theportion blocking material portion 117.

FIG. 2F illustrates a transistor structure 214 similar to transistorstructure 212, after the formation of gate stack 129. As shown, gatestack 129 may be formed on semiconductor fin 104 and between gatesidewall spacers 122, 123. Gate stack 129 may include any suitablematerial or materials. For example, gate stack 129 may include a gatedielectric 130 such as a high-k gate dielectric and a gate electrode 131such as a metal gate electrode. Gate stack 129 may be formed using anysuitable technique or techniques such as conformal deposition,deposition, and CMP techniques or the like. As shown, in some examples,gate dielectric 130 may be formed on a surface of semiconductor fin 104.In other examples, gate dielectric 130 may also be formed on sidesurfaces of gate sidewall spacers 122, 123 such that gate electrode 131is not in direct contact with gate sidewall spacers 122, 123 forexample. As discussed, in some examples, gate stack 129 may wrap aroundthree sides of semiconductor fin 104 (e.g., a top of semiconductor fin104 as shown in FIG. 2E, and sides of semiconductor fin 104—please referto the plan view of FIG. 1A). In some examples, gate stack 129 may wraparound all sides of semiconductor fin 104 such as in nanowireimplementations.

Transistor structure 214 may form a portion of a transistor of anintegrated circuit. for example, as is discussed further herein. Forexample, a transistor may include gate stack 129 (e.g. a gate) formedover a portion of semiconductor fin 104. The transistor may furtherinclude gate sidewall spacer 122 adjacent to the gate (e.g., adjacent togate stack 129) and a blocking material (e.g., blocking material 125)between gate sidewall spacer 122 and another portion of semiconductorfin 104. Furthermore, the transistor may include a blockingself-assembled monolayer molecule head group, a blocking self-assembledmonolayer molecule tail, a blocking self-assembled monolayer moleculetail functional group, a blocking self-assembled monolayer molecule, ora combination thereof (e.g., remaining self-assembled monolayer portion207) between blocking material 125 and gate sidewall spacer 122. Forexample, carbon or carbon based chains portions from a self-assembledmonolayer may be between blocking material 125 and gate sidewall spacer122. Such a transistor structure or other transistor structuresdiscussed herein may be implemented via a system, platform, computingdevice, or the like as is discussed further herein.

As discussed, FIGS. 2D-2F illustrate an example process flow for theformation of a transistor structure. In other embodiments, otherfabrication operations may be performed on transistor structure 205 ofFIG. 2C such as other replacement gate process flows or the like. Forexample, as discussed, a top of gate 110 may be exposed, sidewallspacers 122, 123 may be formed, and gate 110 may be removed without theintroduction of interlayer dielectric 119. Furthermore, the formation ofother structures such as channel implant regions, source/drain implantregions, and the like have not been discussed for the sake of clarity ofpresentation.

FIG. 4 illustrates an example transistor structure 400 with a blockingmaterial having undercuts, arranged in accordance with at least someimplementations of the present disclosure. As discussed herein, in someexamples, portions of a blocking material may be removed to leave aremaining blocking material portion 117 (e.g., please refer to FIGS. 1Fand 2C). Furthermore, in some examples, a portion of blocking materialportion 117 may be removed to expose a region of semiconductor fin 104(e.g., please refer to FIGS. 1I and 2E) and to form remaining blockingmaterial 125. In such examples, one or more undercuts may be formed inremaining blocking material 125. For example, as shown in FIG. 4,transistor structure 400 may include gate stack 129 (e.g., includinggate dielectric 130 and gate electrode 131) disposed over a portion ofsemiconductor fin 104. Furthermore, transistor structure 400 may includeblocking material 125 between gate sidewall spacer 122 and anotherportion of semiconductor fin 104.

As shown, in some examples, blocking material 125 may include undercut401 and/or undercut 402. For example, undercut 401 may be formed duringthe removal of blocking material 108 to form blocking material portion117 (e.g., please refer to FIGS. 1F and 2C). As discussed, such blockingmaterial 108 may be removed via a selective wet etch process. Forexample, undercut 401 may be substantially rounded as shown due to anisotropic etch of blocking material 108. In some examples, blockingmaterial 125 may include undercut 402. For example, undercut 402 may beformed during the removal of a portion of blocking material portion 117to expose semiconductor fin 104 (e.g., please refer to FIGS. 1I and 2E).As discussed, such portion of blocking material portion 117 may beremoved using a selective wet etch process. For example, undercut 402may be substantially rounded as shown due to an isotropic etch ofportion of blocking material portion 117 to form blocking material 125.As discussed, in various examples, only undercut 401, only undercut 402,both of undercuts 401, 402, or no undercuts may be formed in blockingmaterial 125. Furthermore, in some examples, as discussed herein withrespect to FIGS. 2A-2F, transistor structure 400 may include portions orentireties of self-assembled monolayer molecules between blockingmaterial 125 and gate sidewall spacer 122. Also, as discussed, in someexamples, semiconductor fin 104 may be implemented as a nanowire. Insome examples, the nanowire may have a substantially circular crosssection and, in such examples, undercut 401 and/or undercut 402 mayinclude a ring around the nanowire structure.

FIG. 5 illustrates an example transistor structure 500 with a sidewallspacer having a tapered portion, arranged in accordance with at leastsome implementations of the present disclosure. As discussed herein, insome examples, a conformal layer may be selectively formed on gate 110but not on portions of blocking material 108 and/or blockingself-assembled monolayer 201 (e.g., please refer to FIGS. 1E and 2B), Insome examples, a tapered portion or rounded portion may be formed in theconformal layer adjacent to semiconductor fin 104 such that theresultant gate sidewall spacers include such a tapered or roundedportion. For example, as shown in FIG. 5, transistor structure 500 mayinclude gate stack 129 (e.g., including gate dielectric 130 and gateelectrode 131) disposed over a portion of semiconductor fin 104.Furthermore, transistor structure 500 may include blocking material 125between gate sidewall spacer 122 and another portion of semiconductorfin 104.

Also as shown, gate sidewall spacer 122 may include a tapered portion501. For example, such a tapered portion 501 may be formed during theformation of selective conformal layer 112 due to a relatively highselectivity of growth between gate 110 and blocking material 108 and/orblocking self-assembled monolayer 201 (e.g., please refer to FIGS. 1Eand 2B). For example, gate 110 may seed or provide growth for selectiveconformal layer 112 while blocking material 108 and/or blockingself-assembled monolayer 201 may resist the growth of selectiveconformal layer 112 causing tapered portion 501. As shown, in someexamples, gate sidewall spacer 122 may include a tapered portion such astapered portion 501. In other examples, gate sidewall spacer 122 mayinclude a rounded portion, an undercut portion, or the like due toblocking material 108 and/or blocking self-assembled monolayer 201resisting growth of selective conformal layer 112. As shown, sucheffects may cause a smaller blocking material 125 to be between gatesidewall spacer 122 and semiconductor fin 104. Furthermore, in someexamples, as discussed herein with respect to FIGS. 2A-2F, transistorstructure 500 may include portions or entireties of self-assembledmonolayer molecules between blocking material 125 and gate sidewallspacer 122.

FIG. 6 illustrates an example transistor structure 600 with an implantregion, arranged in accordance with at least some implementations of thepresent disclosure. As discussed herein, in some examples, an implantregion may be formed in regions of semiconductor fin 104 (e.g., pleaserefer to FIG. 1B). Such an implant region may be used to form, increasethe depth of, or enhance the coverage of a subsequently formed blockingmaterial (e.g., please refer to FIG. 1D). For example, an implant regionmay remain within blocking material 125 and/or portions of semiconductorfin 104. For example, as shown in FIG. 6, transistor structure 600 mayinclude gate stack 129 (e.g., including gate dielectric 130 and gateelectrode 131) disposed over a portion of semiconductor fin 104.Furthermore, transistor structure 600 may include blocking material 125between gate sidewall spacer 122 and another portion of semiconductorfin 104. For example, a portion or an entirety of blocking material 125may include an implant region and/or an implant species as discussedherein. Also as shown, transistor structure 600 may include an implantregion 601 within semiconductor fin 104. Implant region 601 may beformed during an implant of sacrificial gate 110 for example. Implantregion 601 may have any suitable depth, concentration and implantconcentration profile. As discussed, in some examples, implant region601 may include a nitrogen implant species. In other examples, implantregion 601 may include one or more of silicon, argon, helium, xenon,oxygen, boron, phosphorus, arsenic, antimony or carbon. Furthermore, insome examples, as discussed herein with respect to FIGS. 2A-2F,transistor structure 600 may include portions or entireties ofself-assembled monolayer molecules between blocking material 125 andgate sidewall spacer 122.

As shown in FIG. 6, in some examples, implant region 601 may comprises asubstantially consistent implant region across semiconductor fin 104that extends under gate sidewall spacer 122. In other examples, implantregion 601 may not extend within semiconductor fin 104 and, in suchexamples, the implant region may be contained within blocking material125.

FIG. 7 is a flow diagram illustrating an example process for forming atransistor structure using selective gate spacer techniques, arranged inaccordance with at least some implementations of the present disclosure.For example, method 700 may be implemented to fabricate transistorstructures 128, 214, 400, 500, 600, or any other transistor structuresas discussed herein. In the illustrated implementation, process 700 mayinclude one or more operations as illustrated by operations 701-704.However, embodiments herein may include additional operations, certainoperations being omitted, or operations being performed out of the orderprovided.

Method 700 may begin at operation 701, “Form a Blocking Material on aSemiconductor Fin”, where a blocking material may be formed on asemiconductor fin. In an embodiment, blocking material 108 may be formedon semiconductor fin 104 as discussed herein with respect to FIG. 1B.For example the blocking material may include one or more of siliconoxide, silicon oxynitride, silicon nitride, silicon carbide, siliconoxycarbide, or a metal oxide such as aluminum oxide.

Method 700 may continue at operation 702, “Dispose a Gate on theBlocking Material”, where a gate may disposed on at least a portion ofthe blocking material such that the gate and the blocking materialcomprise different surface chemistries as discussed herein. In anembodiment, gate 110 may be formed over blocking material 108 (andsemiconductor fin 104) as discussed herein with respect to FIG. 1C. Insome examples, as discussed herein, gate 110 may be a sacrificial ordummy gate such that a replacement gate process may be implemented.

Method 700 may continue at operation 703, “Selectively Form a ConformalLayer on the Gate”, where a selective conformal layer may be formed onthe gate such that the conformal layer has an etch selectivity withrespect to the blocking material and such that the conformal layer isnot formed on at least a portion of the blocking material. In anembodiment, selective conformal layer 112 may be formed on gate 110 asdiscussed herein with respect to FIG. 1E. In some examples, an optionalimplant region may be formed in gate 110 prior to forming selectiveconformal layer 112. In some examples, selective conformal layer 112 maybe formed on gate 110 via an implant as discussed with respect to FIG.1D. In some examples, a blocking self-assembled monolayer may be formedon the blocking material prior to forming the selective conformal layeras discussed herein with respect to FIGS. 2A and 2B. In an embodiment,blocking self-assembled monolayer 201 may be formed on a portion ofblocking material 208 prior to forming selective conformal layer 112 asdiscussed herein.

Method 700 may continue at operation 704, “Remove Exposed Portions ofthe Blocking Material”, where exposed portions of the blocking layer maybe removed. For example, as discussed, the blocking material and thegate may have an etch selectively therebetween such that exposedportions of the blocking material may be removed via a selective etchprocess. In an embodiment, portions of blocking material 108 may beremoved to form remaining blocking material portion 117 as discussedherein with respect to FIG. 1F. In examples where a blockingself-assembled monolayer are implemented, exposed portions of theblocking self-assembled monolayer may also be removed as discussedherein with respect to FIG. 2C.

As discussed, in some examples, the gate formed at operation 702 may bea sacrificial or dummy gate. In such examples, a bulk dielectric mayoptionally be formed over the described structure and a planarizationoperation such as a chemical mechanical polish (CMP) operation mayremove portions of the bulk dielectric and expose the sacrificial gateas well as form gate sidewall spacers (e.g., please refer to FIGS. 1Hand 2D). The sacrificial gate may thereafter be removed and remainingportions of the blocking layer and/or the blocking self-assembledmonolayer may be removed within the gate region (e.g., please refer toFIGS. 1I and 2E) leaving blocking material portions and/orself-assembled monolayer molecule portions or entireties thereof betweenthe gate sidewall spacers and the semiconductor fin. Subsequently, agate such as a high-k metal gate may be formed within the gate opening(e.g., please refer to FIGS. 1J and 2F). Such a transistor structure maybe further processed to form source and drains, contacts to the gate andsource/drains, and metal interconnects to form a transistor device suchas an integrated circuit. As discussed herein, an interlayer dielectric(e.g., interlayer dielectric material 119) may be formed prior toexposing gate 110. In other examples, no such interlayer dielectric maybe used.

As discussed, method 700 and other operations discussed herein may beimplemented to fabricate transistor structures. Any one or more of theoperations of method 700 (or the operations discussed herein withrespect to FIGS. 1A-1J or FIGS. 2A-2F) may be undertaken in response toinstructions provided by one or more computer program products. Suchprogram products may include signal bearing media providing instructionsthat, when executed by, for example, a processor, may provide thefunctionality described herein. The computer program products may beprovided in any form of computer readable medium. Thus, for example, aprocessor including one or more processor core(s) may undertake one ormore of the described operations in response to instructions conveyed tothe processor by a computer readable medium.

Furthermore, any one or more of the operations of method 700 (or theoperations discussed herein with respect to FIGS. 1A-1J or FIGS. 2A-2F)may be undertaken to form a transistor structure, a transistor, or adevice. For example, selective gate spacer techniques may be used togenerate devices such as transistor devices, memory devices, or thelike. For example, systems, apparatuses or devices may be formed thatinclude a device layer such as a semiconductor substrate and one or moreintegrated circuit structures coupled to (e.g., on and/or within thesemiconductor substrate) the semiconductor substrate such that the oneor more integrated circuit structures are fabricated using techniquesdiscussed herein.

For example, apparatuses or devices may be formed that include a devicelayer such as a semiconductor substrate and one or more integratedcircuit structures coupled to the semiconductor substrate such that theone or more integrated circuit structures are fabricated by forming ablocking material on a semiconductor fin, disposing a gate on at least afirst portion of the blocking material, wherein the gate and theblocking material comprise different surface chemistries, selectivelyforming a conformal layer on the gate, wherein the conformal layer hasan etch selectivity with respect to the blocking material and whereinthe conformal layer is not formed on at least a second portion of theblocking material, and removing exposed portions of the blockingmaterial. Such integrated circuit structures may be further fabricatedusing any techniques discussed herein. For example, such integratedcircuit structures may be integrated into platforms and/or computingdevices as discussed herein with respect to FIGS. 8 and 9.

FIG. 8 is an illustrative diagram of a mobile computing platform 800employing an IC with transistor(s) fabricated via selective gate spacertechniques, arranged in accordance with at least some implementations ofthe present disclosure. A transistor fabricated or formed via theselective gate spacer techniques discussed may be formed using anytechnique or techniques as discussed herein. Mobile computing platform800 may be any portable device configured for each of electronic datadisplay, electronic data processing, wireless electronic datatransmission, or the like. For example, mobile computing platform 800may be any of a tablet, a smart phone, a netbook, a laptop computer,etc. and may include a display screen 805, which in the exemplaryembodiment is a touchscreen (e.g., capacitive, inductive, resistive,etc. touchscreen), a chip-level (SoC) or package-level integrated system810, and a battery 815.

Integrated system 810 is further illustrated in the expanded view 820.In the exemplary embodiment, packaged device 850 (labeled“Memory/Processor” in FIG. 8) includes at least one memory chip (e.g.,RAM), and/or at least one processor chip (e.g., a microprocessor, amulti-core microprocessor, or graphics processor, or the like). In anembodiment, the package device 850 is a microprocessor coupled to anSRAM cache memory. In some examples, one or both of the at least onememory and the at least one processor chip includes transistor(s)fabricated via the selective gate spacer techniques discussed herein.For example, a transistor of one or both of the processor or memory mayinclude a gate disposed over at least a first portion of a semiconductorfin, a gate sidewall spacer adjacent to the gate, a blocking materialbetween a second portion of the semiconductor fin and the gate spacer,wherein the gate sidewall spacer has an etch selectivity with respect tothe blocking material, and/or other features as discussed herein. Forexample, the transistor may also include a blocking self-assembledmonolayer molecule or a blocking self-assembled monolayer moleculeportion (e.g., head group, tail, functional tail group, or a portion ofa tail) between the blocking material and the gate sidewall spacer.Other example transistors may include an implant region within thesemiconductor fin and under the blocking material.

Packaged device 850 may be further coupled to (e.g., communicativelycoupled to) a board, a substrate, or an interposer 860 along with, oneor more of a power management integrated circuit (PMIC) 830, RF(wireless) integrated circuit (RFIC) 825 including a wideband RF(wireless) transmitter and/or receiver (TX/RX) (e.g., including adigital baseband and an analog front end module further comprises apower amplifier on a transmit path and a low noise amplifier on areceive path), and a controller thereof 835. In general, packaged device850 may be also be coupled to (e.g., communicatively coupled to) displayscreen 805.

Functionally, PMIC 830 may perform battery power regulation, DC-to-DCconversion, etc., and so has an input coupled to battery 815 and with anoutput providing a current supply to other functional modules. In anembodiment, PMIC 830 may perform high voltage operations. As furtherillustrated, in the exemplary embodiment, RFIC 825 has an output coupledto an antenna (not shown) to implement any of a number of wirelessstandards or protocols, including but not limited to Wi-Fi (IEEE 802.11family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution(LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT,Bluetooth, derivatives thereof, as well as any other wireless protocolsthat are designated as 3G, 4G, 5G, and beyond. In alternativeimplementations, each of these board-level modules may be integratedonto separate ICs coupled to the package substrate of packaged device850 or within a single IC (SoC) coupled to the package substrate of thepackaged device 850.

FIG. 9 is a functional block diagram of a computing device 900, arrangedin accordance with at least some implementations of the presentdisclosure. Computing device 900 may be found inside platform 1000, forexample, and further includes a motherboard 902 hosting a number ofcomponents, such as but not limited to a processor 901 (e.g., anapplications processor) and one or more communications chips 904, 905.Processor 901 may be physically and/or electrically coupled tomotherboard 902. In some examples, processor 901 includes an integratedcircuit die packaged within the processor 901. In general, the term“processor” may refer to any device or portion of a device thatprocesses electronic data from registers and/or memory to transform thatelectronic data into other electronic data that may be stored inregisters and/or memory.

In various examples, one or more communication chips 904, 905 may alsobe physically and/or electrically coupled to the motherboard 902. Infurther implementations, communication chips 904 may be part ofprocessor 901. Depending on its applications, computing device 900 mayinclude other components that may or may not be physically andelectrically coupled to motherboard 902. These other components mayinclude, but are not limited to, volatile memory (e.g., DRAM) 907, 908,non-volatile memory (e.g., ROM) 910, a graphics processor 912, flashmemory, global positioning system (GPS) device 913, compass 914, achipset 906, an antenna 916, a power amplifier 909, a touchscreencontroller 911, a touchscreen display 917, a speaker 915, a camera 903,and a battery 918, as illustrated, and other components such as adigital signal processor, a crypto processor, an audio codec, a videocodec, an accelerometer, a gyroscope, and a mass storage device (such ashard disk drive, solid state drive (SSD), compact disk (CD), digitalversatile disk (DVD), and so forth), or the like.

Communication chips 904, 905 may enables wireless communications for thetransfer of data to and from the computing device 900. The term“wireless” and its derivatives may be used to describe circuits,devices, systems, methods, techniques, communications channels, etc.,that may communicate data through the use of modulated electromagneticradiation through a non-solid medium. The term does not imply that theassociated devices do not contain any wires, although in someembodiments they might not. Communication chips 904, 905 may implementany of a number of wireless standards or protocols, including but notlimited to those described elsewhere herein. As discussed, computingdevice 900 may include a plurality of communication chips 904, 905. Forexample, a first communication chip may be dedicated to shorter rangewireless communications such as Wi-Fi and Bluetooth and a secondcommunication chip may be dedicated to longer range wirelesscommunications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, andothers.

As used in any implementation described herein, the term “module” refersto any combination of software, firmware and/or hardware configured toprovide the functionality described herein. The software may be embodiedas a software package, code and/or instruction set or instructions, and“hardware”, as used in any implementation described herein, may include,for example, singly or in any combination, hardwired circuitry,programmable circuitry, state machine circuitry, and/or firmware thatstores instructions executed by programmable circuitry. The modules may,collectively or individually, be embodied as circuitry that forms partof a larger system, for example, an integrated circuit (IC), systemon-chip (SoC), and so forth.

While certain features set forth herein have been described withreference to various implementations, this description is not intendedto be construed in a limiting sense. Hence, various modifications of theimplementations described herein, as well as other implementations,which are apparent to persons skilled in the art to which the presentdisclosure pertains are deemed to lie within the spirit and scope of thepresent disclosure.

The following examples pertain to further embodiments.

In one or more first embodiments, a method for fabricating a transistorcomprises forming a blocking material on a semiconductor fin, disposinga gate on at least a first portion of the blocking material, wherein thegate and the blocking material comprise different surface chemistries,selectively forming a conformal layer on the gate, wherein the conformallayer has an etch selectivity with respect to the blocking material andwherein the conformal layer is not formed on at least a second portionof the blocking material, and removing exposed portions of the blockingmaterial.

Further to the first embodiments, the method further comprises forming,prior to selectively forming the conformal layer, a blockingself-assembled monolayer on at least a portion of the blocking material.

Further to the first embodiments, the method further comprises forming,prior to selectively forming the conformal layer, a blockingself-assembled monolayer on at least a portion of the blocking material,wherein the blocking self-assembled monolayer comprises molecules havingat least head groups and tails, wherein the head groups comprise atleast one of a siloxane, a silyl chloride, an alkene, an alkyne, anamine, a phosphine, a thiol, a phosphonic acid, or a carboxylic acid.

Further to the first embodiments, the method further comprisesperforming, prior to selectively forming the conformal layer on thegate, an implant into the gate to form an implant region within thegate.

Further to the first embodiments, performing, prior to selectivelyforming the conformal layer on the gate, an implant into the gate toform an implant region within the gate, wherein the gate comprisespolysilicon, the implant comprises a nitrogen implant, and the blockingmaterial comprises silicon oxide.

Further to the first embodiments, performing, prior to selectivelyforming the conformal layer on the gate, an implant into the gate toform an implant region within the gate, wherein the gate comprisespolysilicon, the implant comprises an amorphization implant, andselectively forming the conformal layer comprises a carbon depositionand rapid thermal processing to form a silicon carbide conformal layer.

Further to the first embodiments, the method further comprises forming,prior to selectively forming the conformal layer, a blockingself-assembled monolayer on at least a portion of the blocking materialand/or performing, prior to selectively forming the conformal layer onthe gate, an implant into the gate to form an implant region within thegate.

Further to the first embodiments, selectively forming the conformallayer on the gate comprises a single deposition operation comprising atleast one of a plasma exposure, an atomic layer deposition, a molecularlayer deposition, or a chemical vapor deposition.

Further to the first embodiments, selectively forming the conformallayer on the gate comprises performing an implant into the gate to formthe conformal layer.

Further to the first embodiments, the blocking material comprises atleast one of silicon oxide, silicon oxynitride, silicon nitride, siliconcarbide, silicon oxycarbide, or aluminum oxide.

Further to the first embodiments, the conformal layer comprises at leastone of silicon oxide, silicon nitride, silicon oxynitride, siliconcarbide, silicon oxycarbide, boron nitride, boron carbide, boroncarbonitride, boron phosphide, boron sulfide, polyphosphazene, oraluminum oxide.

Further to the first embodiments, wherein the gate comprises asacrificial gate and the method further comprises removing a top portionof the conformal layer to expose the gate and to form gate sidewallspacers from remaining portions of the conformal layer, removing thegate and at least a portion of the blocking material adjacent to thesemiconductor fin and between the gate sidewall spacers, and disposing agate stack on the semiconductor fin and between the gate sidewallspacers.

Further to the first embodiments, the semiconductor fin comprises anundercut fin comprising a nanowire and the gate substantially wrapsaround the semiconductor fin.

In one or more second embodiments, an integrated circuit comprising atransistor includes a gate disposed over at least a first portion of asemiconductor fin, a gate sidewall spacer adjacent to the gate, and ablocking material between a second portion of the semiconductor fin andthe gate spacer, wherein the gate sidewall spacer has an etchselectivity with respect to the blocking material.

Further to the second embodiments, the integrated circuit furthercomprises a blocking self-assembled monolayer molecule head groupbetween the blocking material and the gate sidewall spacer.

Further to the second embodiments, the integrated circuit furthercomprises a blocking self-assembled monolayer molecule head groupbetween the blocking material and the gate sidewall spacer, wherein theblocking self-assembled monolayer molecule head group comprises at leastone of a siloxane, a silyl chloride, an alkene, an alkyne, an amine, aphosphine, a thiol, a phosphonic acid, or a carboxylic acid.

Further to the second embodiments, the integrated circuit furthercomprises a blocking self-assembled monolayer molecule head groupbetween the blocking material and the gate sidewall spacer, wherein theblocking self-assembled monolayer molecule head group comprises at leastone of a siloxane, a silyl chloride, an alkene, an alkyne, an amine, aphosphine, a thiol, a phosphonic acid, or a carboxylic acid, and animplant region within the semiconductor fin and under at least theblocking material.

Further to the second embodiments, the integrated circuit furthercomprises a blocking self-assembled monolayer molecule head groupbetween the blocking material and the gate sidewall spacer, wherein theblocking self-assembled monolayer molecule head group comprises at leastone of a siloxane, a silyl chloride, an alkene, an alkyne, an amine, aphosphine, a thiol, a phosphonic acid, or a carboxylic acid, and animplant region within the semiconductor fin and under at least theblocking material, wherein the implant region comprises at least one ofnitrogen, oxygen, boron, phosphorus, arsenic, antimony, carbon, argon,helium, or xenon.

Further to the second embodiments, the integrated circuit furthercomprises at least one of a blocking self-assembled monolayer moleculehead group or a blocking self-assembled monolayer molecule tail betweenthe blocking material and the gate sidewall spacer and/or an implantregion within the semiconductor fin and under at least the blockingmaterial.

Further to the second embodiments, the blocking material comprisessilicon oxide, the gate sidewall spacer comprises silicon nitride, thegate comprises a gate stack including a high-k gate dielectric and ametal gate on the high-k gate dielectric.

Further to the second embodiments, the blocking material comprises atleast one of silicon oxide, silicon oxynitride, silicon nitride, siliconcarbide, silicon oxycarbide, or aluminum oxide, and wherein theintegrated circuit further comprises an undercut portion under the gatesidewall spacer.

Further to the second embodiments, the gate sidewall spacer comprises atleast one of silicon oxide, silicon, nitride, silicon oxynitride,silicon carbide, silicon oxycarbide, boron nitride, boron carbide, boroncarbonitride, boron phosphide, boron sulfide, polyphosphazene, oraluminum oxide, and wherein the gate sidewall spacer comprises a taperedportion adjacent to the semiconductor fin.

Further to the second embodiments, the blocking material comprises atleast one of silicon oxide, silicon oxynitride, silicon nitride, siliconcarbide, silicon oxycarbide, or aluminum oxide and/or the gate sidewallspacer comprises at least one of silicon oxide, silicon, nitride,silicon oxynitride, silicon carbide, silicon oxycarbide, boron nitride,boron carbide, boron carbonitride, boron phosphide, boron sulfide,polyphosphazene, or aluminum oxide.

Further to the second embodiments, the integrated circuit furthercomprises an undercut portion under the gate sidewall spacer and/or thegate sidewall spacer comprises a tapered portion adjacent to thesemiconductor fin.

Further to the second embodiments, the semiconductor fin comprises anundercut fin comprising a nanowire and the gate substantially wrapsaround the semiconductor fin.

In one or more third embodiments, a system comprises a memory and aprocessor coupled to the memory, the processor comprising a transistorincluding a gate disposed over at least a first portion of asemiconductor fin, a gate sidewall spacer adjacent to the gate, and ablocking material between a second portion of the semiconductor fin andthe gate spacer, wherein the gate sidewall spacer has an etchselectivity with respect to the blocking material.

Further to the third embodiments, the transistor further comprises ablocking self-assembled monolayer molecule head group between theblocking material and the gate sidewall spacer, wherein the blockingself-assembled monolayer molecule head group comprises at least one of asiloxane, a silyl chloride, an alkene, an alkyne, an amine, a phosphine,a thiol, a phosphonic acid, or a carboxylic acid.

Further to the third embodiments, the transistor further comprises animplant region within the semiconductor fin and under at least theblocking material.

Further to the third embodiments, the blocking material comprisessilicon oxide, the gate sidewall spacer comprises silicon nitride, andthe gate comprises a gate stack including a high-k gate dielectric and ametal gate on the high-k gate dielectric.

It will be recognized that the invention is not limited to theembodiments so described, but can be practiced with modification andalteration without departing from the scope of the appended claims. Forexample, the above embodiments may include specific combination offeatures. However, the above embodiments are not limited in this regardand, in various implementations, the above embodiments may include theundertaking only a subset of such features, undertaking a differentorder of such features, undertaking a different combination of suchfeatures, and/or undertaking additional features than those featuresexplicitly listed. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. A transistor comprising: a gate comprising a gatedielectric over a first portion of a semiconductor fin and a gateelectrode over the gate dielectric; a blocking material on a secondportion of the semiconductor fin adjacent the first portion, theblocking material comprising silicon, carbon, and nitrogen; aninterlayer dielectric material on a third portion of the semiconductorfin adjacent to the second portion; and a gate sidewall spacer on theblocking material and adjacent the gate, wherein the blocking materialand the gate sidewall spacer are adjacent to the interlayer dielectricmaterial and between the gate and the interlayer dielectric material. 2.The transistor of claim 1, further comprising: an implant region withinthe semiconductor fin and under at least the blocking material.
 3. Thetransistor of claim 2, wherein the implant region comprises at least oneof nitrogen, oxygen, boron, phosphorus, arsenic, antimony, carbon,argon, helium, or xenon.
 4. The transistor of claim 1, wherein the gatesidewall spacer comprises silicon and nitrogen, the gate dielectriccomprises a high-k gate dielectric and the gate electrode comprises ametal gate.
 5. The transistor of claim 1, wherein the blocking materialcomprises at least one of silicon oxide, silicon oxynitride, siliconnitride, silicon carbide, silicon oxycarbide, or aluminum oxide.
 6. Thetransistor of claim 5, further comprising an undercut portion under thegate sidewall spacer.
 7. The transistor of claim 1, wherein the gatesidewall spacer comprises at least one of silicon oxide, silicon,nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, boronnitride, boron carbide, boron carbonitride, boron phosphide, boronsulfide, polyphosphazene, or aluminum oxide, and wherein the gatesidewall spacer comprises a tapered portion adjacent to thesemiconductor fin.
 8. The transistor of claim 1, wherein thesemiconductor fin comprises an undercut fin comprising a nanowire andthe gate substantially wraps around the semiconductor fin.
 9. A systemcomprising: a memory; and a processor coupled to the memory, theprocessor comprising a transistor comprising: a gate comprising a gatedielectric over a first portion of a semiconductor fin and a gateelectrode over the gate dielectric; a blocking material on a secondportion of the semiconductor fin adjacent the first portion, theblocking material comprising silicon, carbon, and nitrogen; aninterlayer dielectric material on a third portion of the semiconductorfin adjacent to the second portion; and a gate sidewall spacer on theblocking material and adjacent the gate, wherein the blocking materialand the gate sidewall spacer are adjacent to the interlayer dielectricmaterial and between the gate and the interlayer dielectric material.10. The system of claim 9, further comprising: an implant region withinthe semiconductor fin and under at least the blocking material.
 11. Thesystem of claim 10, wherein the implant region comprises at least one ofnitrogen, oxygen, boron, phosphorus, arsenic, antimony, carbon, argon,helium, or xenon.
 12. The system of claim 9, wherein the gate sidewallspacer comprises silicon and nitrogen, the gate dielectric comprises ahigh-k gate dielectric and the gate electrode comprises a metal gate.13. The system of claim 9, wherein the blocking material comprises atleast one of silicon oxide, silicon oxynitride, silicon nitride, siliconcarbide, silicon oxycarbide, or aluminum oxide.
 14. The system of claim13, wherein the transistor further comprises an undercut portion underthe gate sidewall spacer.
 15. The system of claim 9, wherein the gatesidewall spacer comprises at least one of silicon oxide, silicon,nitride, silicon oxynitride, silicon carbide, silicon oxycarbide, boronnitride, boron carbide, boron carbonitride, boron phosphide, boronsulfide, polyphosphazene, or aluminum oxide, and wherein the gatesidewall spacer comprises a tapered portion adjacent to thesemiconductor fin.
 16. The system of claim 9, wherein the semiconductorfin comprises an undercut fin comprising a nanowire and the gatesubstantially wraps around the semiconductor fin.